Move dependencies into rail (from rail_pipelines)

[OliviaLynn]

Problem & Solution Description (including issue #)

Executes my solution described in this comment in issue #123

Code Quality

• [x] My code follows the code style of this project
• [x] I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• [x] My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• [x] Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[ztq1996]

Looks good to me. Echoing the message in the Slack channel, I want to wait a little longer for people to raise opinions about adding/removing packages in the installation list. Let’s set the deadline for Monday next week.